This application is related to Japanese Patent Application No. 2001-112346 filed in Apr. 11, 2001 whose priority is claimed under 35 USC xc2xa7119 the disclosure of which is incorporated by reference in its entirety.
1. Field of the Invention
The present invention relates to a semiconductor device such as, for example, an optical spatial transmitter that performs infrared ray data communication of IrDA (Infrared Data Association) or the like.
2. Description of the Prior Arts
Explained hereinbelow is an optical spatial transmitter having an infrared ray data communication technique of IrDA as a conventional semiconductor device.
The current IrDA standard includes IrDA 1.2 for low power in addition to IrDA 1.0 (transmission speed is 2.4 kbps to 115.2 kbps) and IrDA 1.1 (transmission speed is 9.6 kbps to 4 Mbps). An optical spatial transmitter designed based upon these IrDA standards is used for data communication between each personal computer or between a personal computer and peripheral devices with one-to-one half-duplex operation, or widely used for products such as PDA (Personal Digital (Data) Assistants: personal information terminal) or a cellular phone.
A surface-mounted optical spatial transmitter mounted to these devices will be explained with reference to FIG. 4.
FIG. 4 is a front view showing an essential part of a surface-mounted optical spatial transmitter. In FIG. 4, numeral 4 designates a light-receiving element such as a photodiode to which receiving data in the infrared ray data communication is inputted, 5 an integrated circuit element such as IC (Integrated Circuit) that performs various processings such as amplifying and digitizing the electrical signal from the light receiving element 4 and digitally outputting the same, 6 a light emitting element such as a light emitting diode that outputs transmit data in the infrared ray data communication, 8 a print wiring board, and 1, 2 and 3 respectively an element mounting section, each of which is disposed on the print wiring board 8 and on which the light receiving element 4, the integrated circuit element 5 and the light emitting element 6 are respectively fixed to be mounted with a conductive or insulating adhesive paste. The light receiving element 4, integrated circuit element 5 and light emitting element 6 are generally fixed by a conductive adhesive agent. Numeral 7 denotes a gold wire for wire-bonding each element 4, 5 and 6 to the wiring on the print wiring board 8 to connect each element to the wiring, 9 and 9xe2x80x2 gold wire connecting sections (wire connecting sections) mounted on the print wiring board 8 for a connection of the gold wire 7, and 10 a wiring section mounted on the print wiring board 8 for connecting the element mounting sections 1 and 2 to each gold wire connecting section 9.
As shown in FIG. 4, the light receiving element 4, the integrated circuit element 5 and the light emitting element 6 are respectively fixed to be mounted with an adhesive on each element mounting section 1, 2 and 3 on the print wiring board 8. Each mounted element 4, 5 and 6 is wire-bonded to each metal wiring section 9 and 9xe2x80x2 on the print wiring board 8 with the gold wire 7 to thereby complete the connection. Each metal wiring connecting section 9 is mounted on the same wiring section 10 as the element mounting sections 1 and 2. Specifically, the element mounting sections 1 and 2 are connected to each metal wiring section 9 by each wiring section 10. The metal wiring section 9xe2x80x2 is connected to none of the element mounting sections 1, 2 and 3 via the wiring on the print wiring board 8.
The optical spatial transmitter having the above structure is required to have a miniaturized print wiring board 8 and respective miniaturized semiconductor elements mounted on the print wiring board 8 as a product has been downsized. In order to achieve the miniaturization, the surface area of the print wiring board 8 is made small for narrowing the space between the element mounting sections 1 and 2 and each gold wire connecting section 9, which requires to shorten the wiring section 10.
However, the above-mentioned conventional technique utilizes narrowing the space between the element mounting sections 1, 2 and the gold wire connecting section 9 for shortening the wiring section 10, whereby a paste-like adhesive or its component such as epoxy resin flown out upon manufacturing to be leaked out from the element mounting sections 1, 2 or run spread. The leaked adhesive or component streams down the wiring section 10 and reaches each gold wire connecting section 9.
This leaked adhesive or component causes a poor wire bonding including a state that the gold wire 7 cannot be connected to the gold wire connecting section 9, or a state that the connection intensity becomes weak so that the gold wire 7 is detached from the gold wire connecting section 9. Even though the gold wire 7 is not detached from and connected to the gold wire connecting section 9 upon manufacturing this optical spatial transmitter, a defect may occur such that the gold wire 7 is detached from the gold wire connecting section 9 due to heat stress caused by a reflow in the solder bonding that is applied for mounting the transmitter to the product.
As described above, there has been a problem that, as the optical spatial transmitter is miniaturized, the adhesive or its component is leaked out from the element mounting sections 1, 2 and flown into each gold wire connecting section 9, that leads to the aforementioned defects.
The present invention is accomplished to solve the aforementioned problem, and aims to provide a semiconductor device capable of being miniaturized by preventing the inflow of an adhesive or its component of the components composing the adhesive.
In order to solve the above-mentioned problem, the present invention provides a semiconductor device comprising an element mounting section, a wire connecting section and a wiring section for connecting the element mounting section and the wire connecting section, all of which are provided at least one by one on the same surface of a print wiring board, in which a semiconductor element is fixed to be mounted to the element mounting section with an adhesive and the semiconductor element is wire-bonded to be connected to the wire connecting section, wherein the wiring section is provided with inflow preventing means for preventing the inflow of the adhesive arranged at the element mounting section and the component composing the adhesive into the wire connecting section via the wiring section.
Providing the inflow preventing means at the wiring section that connects the element mounting section to the wire connecting section can prevent the inflow of the adhesive or its component into the wire connecting section. Therefore, the print wiring board can be miniaturized without considering the defect in wire bonding. This can miniaturize the semiconductor device itself.
Further, the present invention provides that, in the above-mentioned semiconductor device, wherein the wiring section includes a belt-like zone connecting the element mounting section with the wire connecting section, the inflow preventing means has a resist member provided on a belt-like zone of the wiring section.
According to the present invention, the resist member is applied or printed on the wiring section that connects the element mounting section to the wire connecting section, whereby the paste-like adhesive or its component is dammed up. Consequently, the inflow of the adhesive or the like into the wire connecting section can be prevented. Therefore, the print wiring board can be miniaturized without considering the defect in wire bonding. This can miniaturize the semiconductor device itself.
Moreover, the present invention provides that, in the above-mentioned semiconductor device, wherein the wiring section includes a belt-like zone connecting the element mounting section with the wire connecting section, and the inflow preventing means is formed of a portion of the belt-like zone which is narrower than other part thereof.
According to the present invention, the portion of the wiring section that is formed to be narrower hinders the paste-like adhesive or its component from flowing in, to thereby be capable of preventing the inflow of the adhesive or the like into the wire connecting section. Therefore, the print wiring board can be miniaturized without considering the defect in wire bonding. This can miniaturize the semiconductor device itself.
Additionally, the present invention provides that, in the above-mentioned semiconductor device, the inflow preventing means is formed such that a plurality of curved sections are formed at a portion of the wiring section.
According to the present invention, forming a plurality of curved sections at the wiring section can substantially lengthen the distance between the element mounting section and the wire connecting section compared to the case where this distance is linked with a straight line that is the shortest route. This can prevent the paste-like adhesive or its component from reaching the wire connecting section, to thereby be capable of preventing the inflow of the adhesive or the like into the wire connecting section. Consequently, the print wiring board can be miniaturized without considering the defect in wire bonding. This can miniaturize the semiconductor device itself.
Further, the present invention provides that, in the above-mentioned semiconductor device, at least two semiconductor elements are mounted on the same surface of the print wiring board, one of which is mounted to the element mounting section, wherein the wire connected to the other semiconductor element is bonded to the wire connecting section.
This structure can miniaturize the print wiring board used for the semiconductor device comprising at least two semiconductor elements, to thereby be capable of miniaturizing the semiconductor device itself.
Moreover, the present invention provides that, in the above-mentioned semiconductor device, a light emitting element, a light receiving element and an integrated circuit element are mounted on the same surface of the print wiring board for forming a spatial optical transmitter, wherein one of the semiconductor elements is the light receiving element while the other semiconductor element is the integrated circuit element.
This structure can miniaturize the print wiring board used for the optical spatial transmitter comprised of the light emitting element, light receiving element and the integrated circuit element, to thereby be capable of miniaturizing the semiconductor device itself.